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NASA Technical Reports Server (NTRS) (686.401 recursos)

The NTRS is a valuable resource for students, educators, researchers, and the public for access to NASA's current and historical technical literature since it was first released in 1994. NTRS provides access to approximately 500K aerospace related citations, 90K full-text online documents, and 111K images and videos. NTRS numbers continues to grow over time as new scientific and technical information (STI) is created or funded by NASA. The type of information found in NTRS include: conference papers, images, journal articles, photos, meeting papers, movies, patents, research reports, and technical videos.

Mostrando recursos 181 - 200 de 321.858

  1. Development of Trace Contaminant Control Prototypes for the Primary Life Support System (PLSS)

    Guerrero, Sandra V.; Cosgrove, Joseph E.; Serio, Michael E.; Nalette, Tim; Wojtowicz, Marek; Papale, William; Wilburn, Monique S.
    Results are presented on the development of Trace Contaminant Control (TCC) Prototypes for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). The current TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal, which is non-regenerable, and the carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. Data on sorption and desorption of ammonia and formaldehyde, which are major TCs of concern, as well as pressure-drop calculations were used to design and test 1/6-scale and full-scale trace contaminant control system (TCCS) prototypes....

  2. Test Vehicle Forebody Wake Effects on CPAS Parachutes

    Ray, Eric S.
    Parachute drag performance has been reconstructed for a large number of Capsule Parachute Assembly System (CPAS) flight tests. This allows for determining forebody wake effects indirectly through statistical means. When data are available in a "clean" wake, such as behind a slender test vehicle, the relative degradation in performance for other test vehicles can be computed as a Pressure Recovery Fraction (PRF). All four CPAS parachute types were evaluated: Forward Bay Cover Parachutes (FBCPs), Drogues, Pilots, and Mains. Many tests used the missile-shaped Parachute Compartment Drop Test Vehicle (PCDTV) to obtain data at high airspeeds. Other tests used the Orion...

  3. Isolating Added Mass Load Components of CPAS Main Clusters

    Ray, Eric S.
    The current simulation for the Capsule Parachute Assembly System (CPAS) lacks fidelity in representing added mass for the 116 ft Do ringsail Main parachute. The availability of 3-D models of inflating Main canopies allowed for better estimation the enclosed air volume as a function of time. This was combined with trajectory state information to estimate the components making up measured axial loads. A proof-of-concept for an alternate simulation algorithm was developed based on enclosed volume as the primary independent variable rather than drag area growth. Databases of volume growth and parachute drag area vs. volume were developed for several flight...

  4. First-Principles Modeling Of Electromagnetic Scattering By Discrete and Discretely Heterogeneous Random Media

    Yurkin, Maxim A.; Travis, Larry D.; Dlugach, Janna M.; Panetta, R. Lee; Mishchenko, Michael I.; Yang, Ping; Zakharova, Nadezhda T.; Cairns, Brian; Liu, Li; Bi, Lei
    A discrete random medium is an object in the form of a finite volume of a vacuum or a homogeneous material medium filled with quasi-randomly and quasi-uniformly distributed discrete macroscopic impurities called small particles. Such objects are ubiquitous in natural and artificial environments. They are often characterized by analyzing theoretically the results of laboratory, in situ, or remote-sensing measurements of the scattering of light and other electromagnetic radiation. Electromagnetic scattering and absorption by particles can also affect the energy budget of a discrete random medium and hence various ambient physical and chemical processes. In either case electromagnetic scattering must be...

  5. Radiation Information for Designing and Interpreting Biological Experiments Onboard Missions Beyond Low Earth Orbit

    Straume, T.; Slaba, T.; Bhattacharya, S.; Braby, L. A.
    There is growing interest in flying biological experiments beyond low-Earth orbit (LEO) to measure biological responses potentially relevant to those expected during a human mission to Mars. Such experiments could be payloads onboard precursor missions, including unmanned private-public partnerships, as well as small low-cost spacecraft (satellites) designed specifically for biosentinel type missions. Designing such experiments requires knowledge of the radiation environment and its interactions with both the spacecraft and the experimental payload. Information is provided here that is useful for designing such experiments.

  6. An Autonomous System for Experimental Evolution of Microbial Cultures: Test Results Using Ultraviolet-C Radiation and Escherichia Coli.

    Gentry, Diana; Wang, Jonathan; Arismendi, Dillon; Ouandji, Cynthia; Lee, Alonzo; Blaich, Justin
    At its core, the field of microbial experimental evolution seeks to elucidate the natural laws governing the history of microbial life by understanding its underlying driving mechanisms. However, observing evolution in nature is complex, as environmental conditions are difficult to control. Laboratory-based experiments for observing population evolution provide more control, but manually culturing and studying multiple generations of microorganisms can be time consuming, labor intensive, and prone to inconsistency. We have constructed a prototype, closed system device that automates the process of directed evolution experiments in microorganisms. It is compatible with any liquid microbial culture, including polycultures and field samples,...

  7. Cooling of Electric Motors Used for Propulsion on SCEPTOR

    Derlaga, Joseph M.; Christie, Robert J.; Dubois, Arthur
    NASA is developing a suite of hybrid-electric propulsion technologies for aircraft. These technologies have the benefit of lower emissions, diminished noise, increased efficiency, and reduced fuel burn. These will provide lower operating costs for aircraft operators. Replacing internal combustion engines with distributed electric propulsion is a keystone of this technology suite, but presents many new problems to aircraft system designers. One of the problems is how to cool these electric motors without adding significant aerodynamic drag, cooling system weight or fan power. This paper discusses the options evaluated for cooling the motors on SCEPTOR (Scalable Convergent Electric Propulsion Technology and...

  8. Influence of Aerogel Morphology and Reinforcement Architecture on Gas Convection in Aerogel Composites

    Meyer, Matthew; Rogers, Richard B.; Hurwitz, Frances I.; Guo, Haiquan; DeMange, Jeffrey J.; Richardson, Hayley
    A variety of thermal protection applications require lightweight insulation capable of withstanding temperatures well above 900 C. Aerogels offer extremely low-density thermal insulation due to their mesoporous structure, which inhibits both gas convection and solid conduction. Silica aerogel systems are limited to use temperatures of 600-700 C, above which they sinter. Alumina aerogels maintain a porous structure to higher temperatures than silica, before transforming to -alumina and densifying. We have synthesized aluminosilicate aerogels capable of maintaining higher surface areas at temperatures above 1100 C than an all-alumina aerogel using -Boehmite as the aluminum source and tetraethoxysilane (TEOS) as the silicon...

  9. Approximation of Engine Casing Temperature Constraints for Casing Mounted Electronics

    Culley, Dennis E.; Kratz, Jonathan L.; Chapman, Jeffryes W.
    The performance of propulsion engine systems is sensitive to weight and volume considerations. This can severely constrain the configuration and complexity of the control system hardware. Distributed Engine Control technology is a response to these concerns by providing more flexibility in designing the control system, and by extension, more functionality leading to higher performing engine systems. Consequently, there can be a weight benefit to mounting modular electronic hardware on the engine core casing in a high temperature environment. This paper attempts to quantify the in-flight temperature constraints for engine casing mounted electronics. In addition, an attempt is made at studying...

  10. Modeling an Iodine Hall Thruster Plume in the Iodine Satellite (ISAT)

    Choi, Maria
    An iodine-operated 200-W Hall thruster plume has been simulated using a hybrid-PIC model to predict the spacecraft surface-plume interaction for spacecraft integration purposes. For validation of the model, the plasma potential, electron temperature, ion current flux, and ion number density of xenon propellant were compared with available measurement data at the nominal operating condition. To simulate iodine plasma, various collision cross sections were found and used in the model. While time-varying atomic iodine species (i.e., I, I+, I2+) information is provided by HPHall simulation at the discharge channel exit, the molecular iodine species (i.e., I2, I2+) are introduced as Maxwellian...

  11. QBO Modulation of the Mesopause Gravity Wave Momentum Flux over Tierra del Fuego

    De Wit, R. J.; Fritts, D. C.; Hibbins, R. E.; Janches, D.
    The interannual variability of the mesosphere and lower thermosphere (MLT) gravity wave momentum flux over southern mid latitudes (53.7degS) has been studied using more than 7 years of meteor radar observations at Ro Grande, Argentina. A modulation, with periods similar to that of the equatorial stratospheric quasi-biennial oscillation (QBO), is observed in the vertical flux of zonal as well as meridional momentum. The QBO signal is largest in the zonal component during summer and is in phase with the stratospheric QBO at 50 hPa (approx. 21 km). The relation between the stratospheric QBO and the QBO modulation in the MLT...

  12. Neutral Atmospheric Density Modeling and the Conjunction Assessment Problem

    Hejduk, M. D
    No abstract available

  13. Total Ionizing Dose Test of Microsemi's Silicon Switching Transistors JANTXV2N2222AUB and 2N2907AUB

    Freeman, B.; Yau, K.; Campola, M.
    Microsemi's silicon switching transistors, JANTXV2N2222AUB and 2N2907AUB, were tested for total ionizing dose (TID) response beginning on July 11, 2016. This test served as the radiation lot acceptance test (RLAT) for the lot date code (LDC) tested. Low dose rate (LDR) irradiations were performed in this test so that the device susceptibility to enhanced low dose rate sensitivity (ELDRS) could be determined.

  14. Spaceport Command and Control System Automation Testing

    Plano, Tom
    The goal of automated testing is to create and maintain a cohesive infrastructure of robust tests that could be run independently on a software package in its entirety. To that end, the Spaceport Command and Control System (SCCS) project at the National Aeronautics and Space Administration's (NASA) Kennedy Space Center (KSC) has brought in a large group of interns to work side-by-side with full time employees to do just this work. Thus, our job is to implement the tests that will put SCCS through its paces.

  15. Space Exploration

    Gallagher, Dennis
    New range Passage Tomb may be the first structure with known astronomical significance. It was built around 3,200 B.C. in Ireland. It's central passage allows light end-to-end for about 2 weeks around winter solstice. The Sun, Moon, Planets, and Stars held significance in early times due to the seasons, significance for food crops, and mythology. Citation: Corel Photography and Windows to the Universe The Greek may be among the first to pursue analytical interpretations of what they saw in the sky. In about 280 B.C. Aristarchus suggested Earth revolves around the Sun and estimated the distance between. Around 130 B.C....

  16. Performance of the Widely-Used CFD Code OVERFLOW on the Pleides Supercomputer

    Guruswamy, Guru P.
    Computational performance studies were made for NASA's widely used Computational Fluid Dynamics code OVERFLOW on the Pleiades Supercomputer. Two test cases were considered: a full launch vehicle with a grid of 286 million points and a full rotorcraft model with a grid of 614 million points. Computations using up to 8000 cores were run on Sandy Bridge and Ivy Bridge nodes. Performance was monitored using times reported in the day files from the Portable Batch System utility. Results for two grid topologies are presented and compared in detail. Observations and suggestions for future work are made.

  17. Design and Benchmarking of a Network-In-the-Loop Simulation for Use in a Hardware-In-the-Loop System

    Culley, Dennis; Kratz, Jonathan; Thomas, George; Aretskin-Hariton, Eliot
    Distributed engine control (DEC) systems alter aircraft engine design constraints because of fundamental differences in the input and output communication between DEC and centralized control architectures. The change in the way communication is implemented may create new optimum engine-aircraft configurations. This paper continues the exploration of digital network communication by demonstrating a Network-In-the-Loop simulation at the NASA Glenn Research Center. This simulation incorporates a real-time network protocol, the Engine Area Distributed Interconnect Network Lite (EADIN Lite), with the Commercial Modular Aero-Propulsion System Simulation 40k (C-MAPSS40k) software. The objective of this study is to assess digital control network impact to the...

  18. Software Development for Remote Control and Firing Room Displays

    Zambrano Pena, Jessica
    The Launch Control System (LCS) developed at NASA's Kennedy Space Center (KSC) will be used to launch future spacecraft. Two of the many components of this system are the Application Control Language (ACL) and remote displays. ACL is a high level domain specific language that is used to write remote control applications for LCS. Remote displays are graphical user interfaces (GUIs) developed to display vehicle and Ground Support Equipment (GSE) data, they also provide the ability to send commands to control GSE and the vehicle. The remote displays and the control applications have many facets and this internship experience dealt...

  19. Simscape Modeling Verification in the Simulink Development Environment

    Volle, Christopher E. E.
    The purpose of the Simulation Product Group of the Control and Data Systems division of the NASA Engineering branch at Kennedy Space Center is to provide a realtime model and simulation of the Ground Subsystems participating in vehicle launching activities. The simulation software is part of the Spaceport Command and Control System (SCCS) and is designed to support integrated launch operation software verification, and console operator training. Using Mathworks Simulink tools, modeling engineers currently build models from the custom-built blocks to accurately represent ground hardware. This is time consuming and costly due to required rigorous testing and peer reviews to...

  20. Assembled Article Offgas Testing Exemption Criteria

    Pedley, Mike; Beeson, Harold; Dasgupta, Rajib; Burns, Howard DeWitt; McCoy, Torin; Romoser, Amelia; Harper, Susana Tapia
    No abstract available

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